102 



CRAftS AND INSECTS. 



FIG. 118. 

 Chrysalides. 

 (After Morse.) 



cocoon about itself (Fig. 117). The skin is now cast 

 again, and the insect appears a short, seemingly lifeless 

 pupa or chrysalis (Fig. 118), in which state 

 it remains a greater or less time, finally 

 shedding its skin and appearing a perfect 

 insect or imago. This is known as a con> 

 plete change. Others, 

 as crickets, dragon-flies, 

 grasshoppers (Fig. 119), 

 pass through a partial 

 FiG.ii 9 .-Exampieof change. Insects are found 

 incomplete change everywhere ; far out at 

 or metamorphosis. sea? as the ffalobates (Fig. 

 Young grasshop- x . , 



per : ,, wing just *4*)> m dee P caves > m h t 



appearing. springs, and on the high- 



est glaciers, as the gla- 

 cier-flea (Fig. 133). The bees and ants live seven years, 

 some locusts thirteen or seventeen years, while the May- 

 flies are born and die within twenty-four hours. In all, 

 about 19,000 species of insects are known. 



Sub-Class I. MALACOPODA. 



Peripatus (Peripatida>) r lhz Peripatus is one of the 

 simplest insects, having a long, soft, and cylindrical body, 

 bearing from twenty-eight to sixty-six feet. Upon the 

 head is a pair of jointed extensible antennae ; the feet are 

 soft, and supplied with two claws. When alarmed, it in- 

 stantaneously ejects a secretion that seems to crystallize in 

 the air, forming a complete web in front. It is found in 

 the West Indies, Panama, and Cape of Good Hope 



SUB-CLASS II. CENTIPEDES (Myriapoda). 



General Characteristics. Head free ; thorax and abdo- 

 men continuous ; joints cylindrical, and often numbering 

 two hundred, each bearing a pair of locomotive organs. 



